Currently, paperboard gable top carton seals are created in the following manner. The plastic coating on the paperboard carton is heat activated in any suitable manner, such as hot air, radiated heat, ultrasonic vibration, to a point at which the plastic is tacky. The carton panels are folded and guided together, and then squeezed and cooled, until the seal takes a set. Sufficient pressure must be applied during the sealing operation, to extrude the softened plastic, to fill the pockets and voids created by the folded and abutting multiple paperboard layers.
Depending upon the number of cartons to be squeezed at one time, several hundred to a few thousand pounds of force must be transmitted to the jaws, to generate this pressure. The stroke requirement for the jaws is approximately 1/4 inch.
The force applied to the jaws to squeeze the cartons, is generated by either a straight push, or a leverage/linkage driven design. The straight push design requires large, relatively expensive pneumatic cylinders to push the sealing jaws. The leverage/linkage driven designs can utilize smaller pneumatic cylinders, or a cam, to actuate a linkage system, utilizing leverage ratios to generate the required force at the sealing jaws. However, the linkage components, pivot mounts, and lubrication requirements, are generally quite expensive for this method also.
Langen U.S. Pat. No. 4,735,031, includes a pressing punch (FIGS. 13 and 14) which is pushed by a flexible hose or tube containing a medium under a definite pressure toward a pressing table 55 to weld two folded-over layers of a container collar together.
Taunton U.S. Pat. No. 2,859,796 discloses two flexible tubes (FIGS. 3 and 4) which, when inflated, moves heated resilient material into engagement with a workpiece, such as two plies of heat-sealable ends of a pouch, to seal same.
Notin U.S. Pat. No. 3,808,968 is typical of press devices wherein inflatable hoses are utilized in conjunction with platens to bind two superposed flat articles.